Silicon wafers are used in semiconductor or solar cell fabrication. The wafers are subjected to a manufacturing process that may involve a plurality of machines and a plurality of stations. Thus, the wafers need to be transported from one machine/station to another machine/station one or more times.
The transport of the wafers typically employs apparatuses called end effectors. A typical end effector may be hand-like in appearance where a base unit may attach to a plurality of finger-like extensions (“fingers”). On each of the fingers, a plurality of wafers may be seated atop wafer pads at spaced apart intervals. The end result may be a matrix of wafers supported by the plurality of end effector fingers. The end effector may typically be moved linearly (e.g., forward and backward) as well as rotationally all in the same plane (e.g., x-y axis). The end effector may also be moved in a third direction along a z-axis to provide a full range of motion.
Some end effector designs have difficulty maintaining proper alignment of wafers supported thereon during transport, which may result in wafers being positioned incorrectly during subsequent processes. What is needed is a new end effector design that can maintain proper alignment of wafers supported thereon.